In recent years, much research has been conducted on a problem of compressing code corresponding to a VLIW instruction in order to efficiently use a memory in a system for processing a VLIW instruction.
A general method used to compress code corresponding to a VLIW instruction is No Operation (NOP) compression. NOP compression may be performed in various ways. Conventionally, a separate bit was allocated to some areas of code and then NOP compression was performed. The conventional NOP compression method has a problem of limitation in space for encoding code because a separate area should be allocated to the code.